Hi B.
The first place I would start your research is the tutorial post which has all the basic information, steps, and guidelines that you will need to make the best possible choice for you … and know how to avoid the worst ones.
It sounds like you were shopping at Jordans. As you will read … outside of your testing for PPP (Posture and alignment, Pressure relief, and Personal preferences) … the most important part of a mattress purchase is knowing the specifics of all the layers inside it so that you can identify any weak links in the mattress and make more meaningful comparisons to other mattresses.
You can read more about the Pranasleep mattresses in post #2 here (the links near the end) and I would be very cautious with these because they use more lower density polyfoam in the quilting layers than I would be comfortable with and this can be a weak link in the mattress in terms of durability.
Natura makes some high quality mattresses and most of them don’t have any weak links in their design but you may not be able to find out all the information you need to make an informed choice with some of them and I would also make some very careful value comparisons with these because they tend to be more costly than many other mattresses made by other manufacturers that use similar materials.
Assuming you are talking about Jordans … I would also be cautious with their own brand and make sure that they don’t have any weak links in their design (such as some of the comments here about the Lanai).
As you probably know from some of your reading here … SleepEz is one of the members here which means that I think very highly of them and they compete well with the best in the industry in terms of their quality, value, and service. They make some very high quality/value mattresses that also give you good options after a purchase to either rearrange or exchange layers to fine tune the mattress should you need to and as you mentioned you can also customize each side to the specific needs and preferences of a couple.
The tutorial post also includes a link to a list of some of the other members here that also sell latex mattresses online.
Some of the better local options in and around the Boston area are listed in post #2 here and there are also some good local options available to you as well.
Phoenix